This sept had their royal seat at Maistiu (Mullaghmast) in South Kildare.
He was possibly the son of Muiredach mac Brain (died 818), a previous king.
The king lists in the Book of Leinster have Tuathal succeed his cousin Lorcán mac Cellaig and Tuathal is given a reign of three years giving a reign of 851–854.
[3] Byrne suggests that the root of this apparent confusion lay in the fact that the Uí Dúnlainge kings exercised little real authority due to the aggressions of their western neighbour Cerball mac Dúnlainge (died 888), King of Osraige.
[4] In his death obit in the annals in 854 it states that he was wickedly killed by his own kinsmen.